Applications of index matching in reflectometry, SANS and Brewster angle microscopy

By index matching, we mean, the manipulation of the composition of a material such that heterogeneous regions of a sample present identical refractive indices. Such manipulation is commonly used to exaggerate deviations from bulk properties at the interface between two bulk phases. Whilst index matching is used routinely in small-angle scattering it is in the field of neutron reflection that the technique has only recently been exploited fully. Specific deuteration, either inter- or intramolecular combined with partial structure factor (PSF) analysis has allowed structural detail to be elucidated at resolutions of ∼4 Å. In light scattering Brewster angle microscopy exploits the extinction of ‘p’ polarised light to enhance surface inhomogeneites on the scale of microns.